The present invention relates to a method of making a recuperator, and more particularly to a machine having a plurality of blades in which a sheet is folded thereabout to form a plurality of fins on such sheet.
A recuperator is a special type of heat exchanger and is used with engines, especially gas turbines, to increase the efficiency of such engines. Many of these recuperators are of a primary surface construction. In a primary surface recuperator, a plurality of sheets are stacked in a spaced apart configuration. The spacing therebetween forms a plurality of donor passages and a plurality of recipient passages. In many operations, a hot exhaust gas is passed through the donor passages and an atmospheric temperature intake air is passed through the recipient passages. Heat from the hot exhaust is conducted through the sheet and absorbed by the cooler intake air. Thus, thermal energy from the exhaust gas is extracted and conducted to the intake air increasing the efficiency of the engine.
In many applications the primary surface sheet used in forming the recuperator is very thin, flimsy and difficult to maintain a uniform cross sectional area of the passages between sheets. To enhance the rigidity of the thin sheets, the sheets are formed into an accordion type configuration forming peaks or crests and valleys forming a plurality of upwardly and downwardly opening, transversely extending, relatively deep grooves being relatively closely spaced and having substantially vertical sidewalls or fins. In forming a recuperator using such sheets, the peeks of alternate sheets are aligned and the valleys of alternate sheets are aligned to form the donor passages and the recipient passages. The height and width of the peeks and valleys must be maintained very accurately to insure the effectiveness of the recuperators. For example, if the cross sectional area of either the donor passage or the recipient passage is too small excess resistance will occur and the fluid will resist flowing through the respective passage. On the other hand, if the cross sectional area of either the donor passage or the recipient passage is too large the fluid will pass through the passage and fail to donate or receive the heat from the fluid. Additionally, many of the sheets are formed with a serpentined configuration to enhance a controlled turbulent which increases heat conductivity and resulting efficiency.
U.S. Pat. No. 5,674,803 issued on Dec. 9, 1997 to Douglas R. Ervin, Clifford G. Knepper and Thomas K. Quinn discloses such a fin folding machine. In forming the primary surface sheet or plate with the serpentined configuration, the fin folding machine is used. The fin folding machine has a pair of upper and lower clamping tools and a pair of upper and lower forming tools. The clamping and forming tools have an elongated plate to which is attached a tool holder having a tool therein. A plurality of cam devices actuate the tool holder and in turn the clamping and forming tools to engage and form a single convolution of the sheet. As the crest and valley is formed the sheet is indexed and the motion of the clamping and forming tools are repeated until the folded sheet is formed having a plurality of crests and valleys. As the crests and the valleys are formed the interface of the blades and the sheet causes the tool to wear and must be replaced. Additionally, as the cams wear the accuracy of the machine diminishes to a level wherein the folded sheet is out of tolerance. In order to insure the consistency, accuracy and uniformity of the sheet and the resulting efficiency of the recuperator the fin folding machine will need to be rebuild or replaced. And, as the need for additional machines arise the accuracy between fin folding machines must be maintained.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the invention a method of setting a plurality of tools in a fin folding machine to a preestablished position is disclosed. The fin folding machine has a base, a pair of vertical side support members extending from the base and a top support member spaced from the base and attached to the pair of vertical side support members. The base, pair of vertical side support members, and the top support member define an opening therebetween. The fin folding machine has the plurality of tools movably positioned within the opening and forms a corrugated sheet of material having a plurality of deep serpentine upper grooves and a plurality of deep serpentine lower grooves. The method of the setting the plurality of tools in the fin folding machine comprising the following steps: positioning a bar within the opening; attaching the bar to one of the plurality of tools; monitoring a position of the bar with respect to the one of the plurality of tools; monitoring a position of the bar with respect of each of the other ones of the plurality of tools; and adjusting the monitored position of each of the other ones of the plurality of tools to a preestablished relationship to the one of the plurality of tools having the bar attached thereto.
In another aspect of the invention a bar positions a plurality of tools in a fin folding machine. The bar is comprised of a plurality of sides having a preestablished configuration and a plurality of sensor bores are positioned in respective ones of the plurality of sides.
And, in another aspect of the invention a fin folding machine has a base, a pair of vertical side support members extending from the base and a top support member is spaced from the base and attached to the pair of vertical side support members. The base, pair of vertical side support members, and the top support member defines an opening therebetween. The fin folding machine has a plurality of tools movably positioned within the opening and a bar has a plurality of sensors positioned therein. The bar positions a plurality of the plurality of tools into a preestablished position one relative to another of the plurality of tools